●过去式 过去分词是thought thought

●thought 又是名词“思想，想法”

It's the thought that counts.

心意很重要/贵在有心。

Different people have different thoughts.

不同的人有不同的想法。

●I think 作插入语,位置灵活，可置于句首句尾句中，用逗号隔开。

I think,Tom has known the truth. Tom,I think, has known the truth.

Tom has known the truth, I think.

我想汤姆已经知道真相了。

●do you think作插入语，后接宾语从句，疑问词放在句首，句中没有逗号，句式结构是：

疑问词+do you think+陈述语序的句子…？

What do you think made him so angry? 你认为是什么事让他那么生气？ Who do you think he is running after? 你认为他在追赶谁？

●I think+(that)+宾语从句

I thinkTom has known the truth.

I think后没有标点符号，它不是插入语，是主句，Tom has known the truth.是宾语从句。

●否定前移及反意问句 I think后跟宾语从句，变否定句时，否定词需要前移，即把主句I think变成否定句，不能把宾语从句变否定句。

I don't think Tom has known the truth.我想汤姆不知道真相。

● it 作think的形式宾语，真正的宾语是后面的动词不定式，句式解构为：

主+think+it+adj+(for sb)+to do

I think it helpful to learn a foreign language.

我认为学一门外语是有帮助的。

可改为宾语从句：

I think (that) it's helpful to learn a foreign language.

●think+n./pron.+adj 形容词作宾语补足语。

I think him very clever.

=I think (that) he is very clever.

●I think so.

I don't think so.

●think 短语

① think of 想到，记得，认为,of是介词。 She always thinks of others 。

她总是为别人着想。

I can't think of her name.

我想不起她的名字。

② think about 思考，考虑，认为，about是介词。

He is thinking about a math problem. 他在思考一道数学难题。

※当表示“认为，对某人某物有什么看法”时，think of和think about可以互换。 What do you think of/about the film? 你认为这部电影怎么样？

③ think over 仔细考虑，over是副词。 宾语是代词时，要放在think over中间。

Think over, and you will find a good way.仔细想想，你就会找到好办法的。 Let me think it over.让我仔细想想。

④ think twice( about) 再三思考，慎重考虑，和think over意思接近。

You must think twice before you make any big decision.

做任何重大决定之前，你必须要三思。

Think twice about it and you will have a good idea.慎重考虑一下，你就会有好注意的。

⑤ think up =come up with 想出,提出(主意，计划等）

We have thought up a good idea.

我们想出了一个好主意。

⑥ think hard 仔细想，费力地琢磨，深思

They are thinking hard about their holiday plans.他们正在费劲地琢磨他们的假期计划。

其实，还是think about 的用法，只不过多了一个副词hard。

⑦ think back to 回想起，回忆起

I often think back to those times. 我经常回想起那些时候。